Machine dishwashing compositions comprising one or more nonionic surfactants long have been known and are commercially available. For optimum results the detergent composition should be capable of adequate soil removal when used under the varied conditions commonly encountered by the consumer in a typical household machine dishwasher. The operating conditions commonly encountered in household dishwashers used by the public frequently encompass a range of diverse operating temperatures that often are influenced by the temperature of the water currently being supplied by the household hot-water heater for the diverse hot-water requirements of the home. At a time of high demand for hot water within the household, the water temperature may be considerably lower than when there is no competition for the finite supply of hot water. It further is recognized that optimum soil removal commonly is achieved at higher water temperatures. Additionally, it is recognized that certain types of soils, such as protein soil from eggs and/or milk products, in conjunction with the detergent, can enhance the generation of harmful quantities of foam within the dishwasher that serve to impede the removal of soil from dishes by reducing the impact of a stream of water thrown by the spray arm or impeller of the dishwasher.
Representative nonionic surfactants for use in machine dishwashing compositions are disclosed in U.S. Pat. Nos. 4,306,987; 4,411,810; and 4,438,014. Additionally, commonly assigned U.S. Pat. No. 4,272,394 discloses a surfactant composition comprising a blend of nonionic surfactants.
Commonly assigned U.S. patent application Ser. No. 08/261,144 to the same inventors as named herein, entitled "Improved Rinse-Aid Composition Comprising a Blend of Nonionic Surfactants" is filed concurrently herewith.
It is an object of the present invention to provide an improved aqueous machine dishwashing composition that exhibits good soil removal properties and effective protein soil defoaming over an expanded range of operating temperatures.
It is an object of the present invention to provide an improved aqueous machine dishwashing composition that is suitable for use at a temperature of up to at least 140.degree. F. in the absence of deleterious foaming even in the presence of protein soil sometimes encountered during the washing of household dishes.
It is an object of the present invention to provide an improved aqueous machine dishwashing composition that in a preferred embodiment is free of an alkyl phosphate ester defoamer.
These and other objects and advantages of the claimed invention will be apparent to those skilled in the art from the following detailed description and appended claims.